The invention disclosed comprises a system and use method for a vehicular navigation system that does not rely on continuous or frequent GPS satellite signal reception. The invention has self-contained subsystems that provide vehicle speed, compass direction and based on elapsed time, vehicle location.
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1. A system comprising: at least one wheel-rotation sensor operative to detect and convey wheel-rotation data signals; a magnetic sensor operative to detect and convey compass direction data signals for a vehicle's direction of travel; a satellite positioning receiver subsystem operative to receive a plurality of satellite positioning signals then determine and convey the location coordinates of its position; a graphical user interface operative to convey user inputs to an I/O subsystem; said graphical user interface operative to receive and display inputs from said I/O subsystem; a navigation subsystem comprising: a processing unit; maps data memory storage; and program memory; at one least program, executed by said processing unit, operative to direct capturing and storing of a succession of said wheel-rotation data; said at least one program operative to direct capturing and storing of a succession of said location coordinates of said satellite positioning receiver subsystem; said succession of wheel-rotation data and said succession of said location coordinates are captured concurrently; said at least one program operative to direct computing of a first speed based on said succession of said wheel-rotation data; said at least one program operative to direct computing of a second speed based on said succession of said location coordinates; said at least one program operative to compare said first speed to said second speed; said at least one program operative to compute a calibration factor by which said first speed when multiplied by said calibration factor is equal to said second speed; said at least one program operative to multiply later captures of said wheel-rotation data by said first calibration factor and to use result to compute vehicle speed; said at least one program, executed by said processing unit, operative to direct capturing and storing of a succession of said compass direction data; said at least one program operative to direct capturing and storing of a succession of said location coordinates of said satellite positioning receiver subsystem; said succession of said compass direction data and said succession of said location coordinates are captured concurrently; said at least one program operative to direct computing of a first compass direction based on said succession of said compass direction data; said at least one program operative to direct computing of a second compass direction on said succession of said location coordinates; said at least one program operative to compare said first compass direction to said second compass direction; said at least one program operative to compute a signed calibration offset by which said first compass direction when summed with said calibration offset is equal to said second compass direction; and said at least one program operative to add said signed calibration offset to later captures of said compass direction data conveyed by said magnetic sensor subsystem.
A vehicle navigation system improves accuracy by cross-referencing wheel-rotation data, satellite positioning, and compass direction. The system includes sensors to detect wheel rotation, magnetic compass direction, and satellite-based location coordinates. A navigation subsystem processes these inputs, comparing wheel-based speed calculations with satellite-derived speed to generate a calibration factor. This factor adjusts future wheel-rotation data to match satellite speed measurements. Similarly, the system compares compass direction with direction derived from location changes to compute a calibration offset, which corrects compass readings. The navigation subsystem stores maps and executes programs to perform these calculations, ensuring accurate speed and direction data for navigation. The system captures wheel-rotation, compass, and location data concurrently, enabling real-time calibration. This approach enhances navigation reliability by mitigating sensor inaccuracies through continuous cross-verification with independent data sources. The graphical user interface allows user interaction and displays navigation outputs. The system is designed for vehicles, improving navigation accuracy by dynamically aligning sensor data with satellite-based references.
2. A method relying on programmatic calibration of sensor data with corresponding satellite position data comprising: establishing an initial vehicle location; inputting a destination location reference; plotting on a display a route linking said initial vehicle location and said destination location; capturing, with a processing unit, vehicle speed based on wheel-rotation data; capturing, with a processing unit, vehicle direction heading based on magnetic sensor data; tracking vehicle position based on said vehicle speed, said vehicle direction and elapsed time; plotting on said display said vehicle position using said route as a backdrop; establishing an initial vehicle location using received satellite positioning data coordinates; calibrating, with a processing unit, a wheel-rotation sensor against speed derived from said received satellite positioning data coordinates; calibrating, with a processing unit, a magnetic sensor and correcting said magnetic sensor data against direction derived from said satellite positioning data coordinates, storing vehicle location coordinates just prior to power down of vehicle; and using stored said vehicle location coordinates as said initial vehicle location just after powering up of vehicle; and establishing, in the absence of said satellite positioning data, said initial vehicle position based on user input in view of maps data.
This invention relates to a vehicle navigation system that improves positioning accuracy by calibrating onboard sensors using satellite positioning data. The system addresses the problem of inaccurate vehicle tracking when satellite signals are unavailable or degraded, such as in urban canyons or tunnels, by dynamically calibrating wheel-rotation and magnetic sensors against satellite-derived speed and direction data. The method begins by determining the vehicle's initial location, either from satellite coordinates or user input when satellite data is unavailable. A destination is input, and a route is plotted on a display. Vehicle speed is measured using wheel-rotation data, while direction is determined from magnetic sensor readings. The system continuously tracks the vehicle's position by combining speed, direction, and elapsed time, displaying the updated position along the plotted route. To enhance accuracy, the system calibrates the wheel-rotation sensor by comparing its speed readings with those derived from satellite data. Similarly, the magnetic sensor is calibrated and corrected using satellite-derived direction data. Before powering down, the system stores the last known vehicle coordinates, which are used as the initial position upon restarting. If satellite data is unavailable, the initial position is set based on user input and map data. This approach ensures reliable navigation even when satellite signals are intermittent.
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January 8, 2019
November 26, 2019
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